"A" chance? As in, "Life is only a chance (to live)"?
Chance as in a random, unpredictable phenomenon.
Life is chance. Life is only chance. Why the singularity of "a" chance? I would never normally say such a thing as a native speaker.
It might not be ideal as written in English. The meaning is clear from the Czech sentence, though, where it's also a pretty common phrase (probably from the popular song with the same name).
The existence of a Czech song doesn't make the English translation sound any better to me. However pleasant and lovely the original. Can someone please make it acceptable with "a".
I wrote “Life is just chance” and it was still wrong.Maybe if I used “but” it would have been OK, but I always use either “only” or “just” as a translation for “jen” in these Czech modules.
According to ngrams, "...is only chance" is used, so I'm adding it as a possible translation. Also, it makes sense to me, it's less ambiguous than "a chance" which can also mean "opportunity" (and that's not what the Czech sentence means).
What about "Life is just a coincidence."?
It might work, although more accurately, a "coincidence" is something else than a "chance" -- and the corresponding Czech expression is "shoda náhod" (literally an agreement/convergence of chances)